A student has a test tube that contains 50 mL of water. She wants to add a substance to the water that will cause the test tube to become hot to the touch. Which of the following would be best for her to add to the water? A.
a substance that produces a gas when it reacts with water
B.
a substance that does not react with water
C.
a substance that releases heat when it reacts with water
D.
a substance that absorbs heat when it reacts with water

Why are carbon dioxide concentrations expected to increase? a carbon dioxide concentrations are expected to increase, because fossil fuel burning is expected to increase b. carbon dioxide concentrations are expected to increase, because of an increase in agriculture. c.carbon dioxide concentrations are expected to increase, because more land will have to be cleared for increasing populations and agricultural use. d. all of the above select the best answer from the choices provided mark this and return save and exit next submit submit